The purpose of the proposed research is to study the relation of facial pain or, more specifically, the myofascial pain-dysfunction syndrome (MPD) to personal, social, and recent experiential factors that contribute to life stress. MPD is a disorder that has traditionally been treated by dentists. It is, at the same time, a disorder that, in most cases, is without a known etiology. The proposed study will use a prospective case-control design involving MPD clinic patients, MPD patients from a private practice, healthy controls matched to the clinic patients on age and education. Subjects will be followed for one year. Differences between cases and controls are hypothesized with respect to: personal dispositions, specifically, locus of control and sensitization-repression; social supports; recent life events; ways of coping with recent life events. These terms will be incorporated into alternative models of the life stress process which will be tested with dat collected over time. Outcomes to be measured are levels of pain, levels of social disability, demoralization, and treatment seeking.